The present invention relates to cosmetic compositions and methods. In particular it relates to cosmetic compositions for regulating sebum on the skin. These compositions may also include acne treatment actives.
A wide variety of compositions are known in the art for providing cosmetic and/or pharmacologic benefits to human skin. Benefits sought include, for example, prevention, treatment or amelioration of environmental or age-related damage or deterioration of the skin, improved appearance by modifying surface characteristics, improved feel by moisturizing, and prevention or treatment of specific skin disorders. Many conventional cosmetic cream and lotion compositions as described, for example, in Sagarin, Cosmetics Science and Technology, 2nd Edition, Volume 1, Wiley Interscience (1972), and Encyclopedia of Chemical Technology, Third Edition, Volume 7. However, because of the physiological complexity of the skin (manifested, for example, by the skin's inherent barrier characteristics to many materials), the ability of such compositions to provide their intended benefits is often limited.
An important aspect of providing cosmetic and/or therapeutic benefits often includes the control of sebum, or skin oil. Sebum is produced in the sebaceous glands located in the pilosebaceous apparatus of the skin and reaches the skin surface through the duct of the hair follicles. The presence of excessive amounts of sebum on the skin surface often results in an unattractive cosmetic condition commonly known as "oily skin". Sebum also plays an important role in the pathogenesis of acne. Acne is a pilosebaceous disease characterized by comedo, papules, inflamed nodules and superficial pus-filled cysts. The course and severity of acne is determined by the interaction between hormones, keratinization, sebum formation and bacteria. Acne usually begins at puberty, when the pilosebaceous glands increase in size, and sebum synthetic activity is elevated due to increased circulating levels of androgens. Follicular hyperkeratosis can also occur, causing restriction of pilosebaceous follicles and, consequently, comedo or plug formation. The comedo contains sebum, protein debris, and anaerobic microorganisms including Propionibacterium (Corynebacterium) acnes. P. acnes thrive on sebum and generate inflammatory free fatty acids. These acids cause irritation in the follicular wall and can lead to rupture of the follicular wall, inducing an inflamed lesion. In severe cases, this lesion will heal with scarring.
Thus, control of sebum on the surface of skin can provide important benefits in the treatment or prevention of acne, as well as improving the appearance of skin by reducing perceived oiliness and greasiness. A variety of compositions have been described in the art for the regulation of sebum on the skin. Typically, the problem of oily facial skin has been dealt with by frequent cleansing and the use of astringent preparations. Clays, talcs, silicas, starches, polymers, and other similar materials have been also suggested for use in skin care compositions for absorbing sebum and controlling oily skin. Topical or systemic pharmacologic agents have also been suggested, to inhibit the product production of sebum. See Karg, G. et al., "Sebosuppression", Cosmetics & Toiletries, vol. 102, pp. 140-146 (April 1987). Skin care compositions said to affect sebum on the skin are described in U.S. Pat. No. 4,515,784, Bogardus et al., issued May 7, 1985; U.S. Pat. No. 5,073,371, Turner et al., issued Dec. 17, 1991; U.S. Pat. No. 5,073,372, Turner et al., issued Dec. 17, 1991; and U.S. Pat. No. 5,380,528, Alban et al., issued Jan. 10, 1995.
However, many compositions known in the art either provide benefits that are very limited, in terms of degree of efficacy, duration of efficacy, or both. Many such compositions also create undesirable side effects. For example, some compositions may create unacceptable drying, irritation or abrasion of the skin. Others may result in undesirable systemic side effects, such as diuretic activity, inflammation, increased blood pressure and effects on other bodily functions. Furthermore, many products actually contribute to and aggravate oily skin problems. For example, many emulsion products are oil-in-water or water-in-oil emulsions containing high levels of fats and oils. The high levels of fats and oils in these products may, in fact, add to the level of oils on the skin.
Applicants have found that compositions containing certain mixtures of silicone materials, in an emulsion, provide significant benefits for the regulation of sebum on skin. Preferred compositions include sebum controlling materials, or other acne regulating agents. These compositions provide improved cosmetic benefits (such as improvement in the visual appearance and feel of skin), as well as improved application characteristics, compared to compositions amongst those known in the art.